SURGICAL TECHNIQUES 3.doc · Web viewA synthetic graft-usually a straight, Dacron woven tube is sutured to the aorta above and below the aneurysm (fig. 3.4). After the aortic graft

Chapter 3 Surgical Techniques ___________________________________________________________________________

CHAPTER 3

Surgical Techniques

3.1 Introduction

Aneurysmal dilatation of the aorta is an irreversible pathological finding: the norm is

further expansion, except in some individuals where slow growth is visible by

imaging. Fascinating studies from Japan suggest that aortic aneurysms might grow

biphasically, i.e. slow initially, then rapidly and that the growth curve can be

expressed as a bi-exponential equation. These studies reiterate that an aneurysm may

rupture at any time and at any size: there is currently no exact measurement that can

precisely predict when this might occur. Size appears to be the best predictor of

rupture [Don F. du Toit, 1999].

Aneurysm formation and danger of rupture are illustrated by Laplace’s Law

Expansion of an aneurysm is demonstrated by the following equation:

T = Pr.

The larger is the vessel radius (r), the larger is the wall tension (T) required to

withstand a given internal fluid pressure (P). As an aneurysm expands, the tension on

the aortic wall increases. Studies have also shown that aortic aneurysms grow faster

shortly before rupture. Surgery for abdominal aortic aneurysms is recommended if

patient’s aneurysm is larger than 5 cm, nowadays there are two kinds of surgical

techniques, one referred as “open surgery” and the other as “endovascular surgery”.

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Although the former is a much older treatment than the latter (the first open surgery

treatment of AAA dates back to the fifties, whereas the less-invasive endovascular

treatment was performed for the first time in 1991), both of them are widely adopted

to treat the AAAs, this because the surgery team is often forced to chose rather one

than the other. For endovascular repair (EVR) the aneurysm should have suitable

anatomy. If certain anatomic characteristics are not met, open surgery is the only

option.

Endovascular treatment may seem always a better choice than the open surgery;

unfortunately only 15-30% of aneurysm patients are candidates for endograft

placement. Anatomic limitations for the placement of a common stent-graft include

aneurysms that involve the renal arteries, aneurysms with extremely short necks, iliac

vessels that are less than 7 mm or greater than 13.4 mm in diameter, densely calcified

vessels, very small femoral vessels, and severe angulations of the aneurysm neck.

These limitations make preoperative measurement and evaluation of the aneurysm

very important; consequently, both conventional angiography and CT angiography

need to be performed. These imaging procedures can be performed on an out-patient

basis. In summary, endograft placement allows 15-30% of abdominal aortic

aneurysms to be treated by a less invasive procedure that means with a decrease in

morbidity when compared to open surgical repair.

3.2 Open surgery

This method has been performed exclusively for almost 50 years and is one of the

most successful and durable operations. At operations the diseased part of the aorta is

replaced with a Dacron or Teflon graft that carefully matches to the normal aorta and

sutured in place by the surgeon. While ultimately curative, this is an operation that

requires a major abdominal incision and general anesthesia, and the hospital stay

averages 7-10 days for most patients. Even after uncomplicated surgery, it is often 6-8

weeks before patients can return to a full and normal life.

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29

Fig. 3.1 Differences between incisions for the open surgery (on the left) and for the endovascular one (on the right). The length of the incision in

surgery has a great relevance for the risk of infections during the surgery itself. On this point of view the open surgery has a completely

different approach.

Fig. 3.2 This is how an aneurysm appears to the surgeon just before clamping the proximal part of the aorta. It is possible to see how much the sac is stretched, the diameter

is more than 5 cm and the risk of rupture is high.


Surgery to remove an aneurysm is one of the most common vascular procedures; the

operation is usually completed in less than two hours. General anesthesia is given, so

the patient will not be awake and will not feel anything. First the surgeon exposes the

aneurysm via an incision in the abdomen of about 17 to 25 cm long (fig. 3.1, 3.2). The

aorta is clamped above and below the aneurysm to prevent bleeding. The aneurysm is

then opened (fig. 3.3). Any clots and fatty deposits that have lodged in the aneurysm

are removed. A synthetic graft-usually a straight, Dacron woven tube is sutured to the

aorta above and below the aneurysm (fig. 3.4).

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Fig. 3.3

Fig. 3.4


After the aortic graft has been sewn in place and all bleeding spots controlled, the

aneurysm sac, which has been opened along its length, is sewn back up loosely over

the new graft. This prevents the new graft from rubbing against the intestine, which

can damage the intestinal wall. When the graft is in place, the clamps are removed,

allowing blood to flow through the graft and to the legs. Patients are usually

hospitalized for seven to ten days.

With the open surgery it is possible to choose among quite a large class of suitable

stent, this because the surgeon always tries to find the stent that better fit for a

particular patient; the last choice about the kind of stent to be used is often made at

the moment of the opening of the sac.

Advantage of conventional surgery compared to EVR of AAA

Efficacy: elective aneurysmectomy and Dacron prosthetic engraftment is a

definitive and “one-off” operation for abdominal aneurysms despite the

dangers of surgery. The procedure is durable and the problems of

symptomatic aneurysms are cured.

Endoleaks: this problem is a specific drawback of EVR of AAA and does not

occur after following conventional, open surgery. Proximal endoleaks

following the endovascular approach result in expansion of the stented

aneurysm sac, with eventual rupture and death of the patient

Prosthesis: in the event of conventional surgery, the procedure can be easily be

accomplished by use of either woven or knitted Dacron prostheses. A

PTFE prosthesis is also highly suitable. Tissue incorporation and perigraft

healing are far superior with the use of knitted Dacron. Wound healing and

mechanical incorporation are retarded with the use of devices, as woven

Dacron is used. Endoleaks simply do not occur, as back bleeding from the

lumbar and the inferior mesenteric arteries are suture ligated and thus

sealed.

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Prosthetic fabric: Dacron prosthesis used during open surgery has had an

excellent track record. Knitted grafts have to be preclotted because of the

high porosity before use. Woven fabric is less porous and is therefore the

fabric of choice for stent device.

Costs: although this aspect has been intensely debated, it does appear that

uncomplicated surgery is cheaper than EVR of AAA in the long run.

Despite reduced hospital stay and the need for intensive care facilities,

EVR of AAA has the following hidden costs that must be taken into

account:

1. Multiple secondary interventions will be needed in 5-10% of patients

to seal persisting endoleaks

2. Expensive imaging is needed for post-stent surveillance

3. Conventional aortic prostheses used for surgical repair are less

expensive than stent devices.

Remodeling of the aneurysm sac: following the conventional surgery, this

phenomenon has little effect on the long-term results of operation or graft

patency. May et al. of the University of Sidney, Australia, and others have

reported on the late changes in endograft and aneurysm morphology after

stent-graft treatment. Remodeling of the aneurysm sac may contribute to

prosthetic distortion following a reduction in the length of the aneurysm sac

[Don F. du Toit, 1999]. This may involve changes in the shape and position

of the device which could predispose to thrombosis in the endograft or

endoleak formation.

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3.3 Endovascular treatment

Endovascular repair (EVR) of abdominal aortic aneurysm offers the advantage of a

minimally invasive technique, a hospital stay of one to two days, a rapid return to

normal physical activity, and a reduction in the mortality and complication rate when

compared with the conventional surgical procedure.

EVR is well tolerated by elderly patients and many are able to undergo AAA repair

this way, with a reduced need for general anesthesia and blood transfusions. As EVR

of AAA is still in the investigation phase, long-term results are eagerly awaited as

regards the incidence of late endoleak formation. However, it is estimated that the

introduction of the newer, second-generation stent devices will allow between 70-

80% of aneurysms to be treated this way [Don F. du Toit, 1999]. Endovascular repair

of abdominal aortic aneurysm utilizes access to the vascular system, through the

femoral artery(-ies). A graft of appropriate design is positioned and deployed in the

abdominal aorta in order to exclude the aneurysm from the pathway of blood flow and

thus eliminate the risk of rupture (fig. 3.5 and 3.6). This technique uses the same graft

material, woven polyester, as that used for conventional aneurysm repair. A self-

expanding stent with hooks that engage the wall of the aorta and iliac arteries become

a substitute for suture material and is called the attachment system.

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Fig. 3.5 The insertion of the stent with the delivery system (on the left) and an endovascular stent-graft used for AAA repair(0n the right), showing the two self-expanding Z-stents sutured to each end of the Dacron tube graft.


When the operation is completed, there is essentially the same reconstruction as

would have been achieved with conventional open repair with the exception of the

fact that a major abdominal incision is avoided with the substitution of one or two

small incisions over each femoral artery in the groin. For patients with an abdominal

aortic aneurysm that is limited to the aorta, and in whom there is both a neck between

the renal arteries and the aneurysm as well as a neck between the lower portion of the

aneurysm and the iliac bifurcation, a graft of tubular configuration is available (fig.

3.7 and fig. 3.8).

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Fig. 3.6 This picture shows the operative field prepared for the usage of the delivery system. In this case two accesses have been opened using both femoral arteries (it is possible to see the two guide-wires), but if the aneurysm does not involve the iliac

bifurcation it is enough only one of the two accesses to deploy the stent.


The stent design shown in fig. 3.7 is just one of the available configurations, The

scientists are continually looking for the best design in order to obtain an optimal

adaptability of the prosthesis to the aorta, therefore different kinds of frame are

available: zigzag, fishing net configuration, spiral frame etc.

For those patients in whom the abdominal aneurysm extends to the iliac bifurcation, a

bifurcated or Y-shaped graft is available (fig. 3.9). For those patients who have both

an abdominal aortic aneurysm as well as an aneurysm of one or both iliac arteries, the

third option is a tapered tube graft that excludes both the aortic aneurysm and one

iliac aneurysm.

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Fig. 3.8 Tubular stent partially opened.

Fig. 3.7 A detail of the structure of a tubular stent.


The entire operation is executed without any chance to observe the aneurysm directly.

The surgeon works for the whole time on the basis of an X-ray image, just looking at

a screen. The images he can refer to are 2-D, so it is often difficult to know the exact

position of the stent-graft. The only reference upon which the surgeon can count is a

system of radiopaque markers on the vascular prosthesis, which are visible in the X-

ray image. The markers are usually three, one at the proximal part of the stent, one at

the distal part and another in the middle of the prosthesis. When radio-opaque contrast

solution is injected via a catheter an angiogram image is seen on the X-ray screen (fig.

3.10).

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Fig. 3.9 AneurRx® modular endovascular bifurcated prosthesis showing components (A) and complete construction alignment (B).


In aorto-uni-iliac endografting, the contralateral iliac artery aneurysm is secondarily

excluded, and blood flow to the contralateral leg and pelvic circulation is

accomplished with the placement of a subcutaneous crossover graft between the two

femoral arteries. The patient comes to the hospital in the morning of operation and is

taken to the operating room.

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Fig. 3.10 The four images show the screen and the images used by the surgical team during a typical operation. In fig. 3.10b and fig. 3.10c the arrows indicate the aneurysmatic parts of the aorta and it is possible to see the guide-wire that is used to insert the delivery system and

to measure the length of the aneurysm. In fig. 3.10d it is clearly visible the fabric of the prosthesis after the deployment and the markers on the proximal part.

B

A

C D


Using either general anesthesia or regional anesthesia, one or both femoral arteries are

exposed depending upon the type of reconstruction that is required. A needle followed

by a guide wire is then placed in the femoral artery, and the guide wire is extended up

the aorta. An angiogram is obtained in order to provide a roadmap image for

placement of the device. The patient is then anti-coagulated with Heparin and the

femoral artery is clamped. A small transverse opening is then made in the femoral

artery through which a working sheath is inserted. The sheath then provides a blood-

type roadway for placement of the graft/catheter delivery system. If a bifurcated graft

is required or an aortoiliac with femoral-femoral crossover, the contralateral femoral

artery is also exposed. In the case of the bifurcated graft, the contralateral femoral

artery is accessed with a needle puncture followed by the placement of a sheath with a

catheter that has a snare system.

In the case of a tube graft, the graft catheter delivery system is passed up through the

sheath, over the guide wire, and positioned across the aneurysm.

Using remote release levers, the graft is deployed with the upper attachment system

immediately below the renal arteries. Both prostheses, self-expandable and with a

balloon (fig. 3.11), are available. In particular, the self-expandable technology is

based on the use of shape memory alloys (generally Nitinol).

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Fig. 3.11 Balloons on top of catheters, the balloons are inflated with physiologic liquid in order to avoid

air outflow in the case of rupture.


The choice of the one to use is a matter of the experience of the surgeon; nowadays a

little has been written about the best configuration for the stents and the research is in

the hands of the manufactures that try to differentiate their own products (fig. 3.12).

Nowadays, this kind of prostheses are made by shaping a Nitinol wire to remember

what will be its final shape in the aorta, than the stent-graft is deformed to fit into the

delivery system. When the prosthesis is in place, the delivery system is opened

gradually and the graft is so exposed to the body temperature and due to this it

recovers the shape that was previously given (fig. 3.13).

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Fig. 3.12 Some models of stents available on the market.

Fig. 3.13 A detail of the upper part of a delivery

system. After the hooks are opened by the surgeon and the hooks on the proximal part of the graft are seated into the wall of the aorta

there is no chance to change the position of the

prosthesis.


In the prosthesis with balloon (fig. 3.14) the balloon is coaxial with the graft within

the delivery system, it is positioned across the attachment site and inflated by the

surgeon to expand the stent against the aortic wall. The lower attachment system is

then deployed immediately proximal to the bifurcation of the iliac arteries. The

balloon is positioned across that attachment site, and the hooks are seated at that

point.

It is even possible to find prostheses that use both shape memory alloys and balloons;

the latter to better adapt the stent-graft to the aortic wall in the attachment sites.

A completion angiogram is then obtained to make certain that the graft is properly

seated and there is no evidence of flow between the graft and the aneurysm.

In the case of the bifurcated graft, initially a wire that is connected to the contralateral

limb of the graft is passed up the ipsilateral side, captured with a snare, and drawn

into the contralateral side. The graft/catheter delivery system is then advanced over a

guidewire, and a jacket that covers the graft is retracted, thus allowing the two limbs

of the graft to separate. The graft is then brought down and appropriately positioned

with the proximal attachment system immediately below the renal arteries and each

iliac graft limb in their appropriate ipsilateral and contralateral iliac arteries. The

attachment systems are then sequentially deployed, and each attachment system is

seated with inflation of a balloon catheter. Once completed, the opening of the

femoral artery(-ies) is repaired.

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Fig. 3.14 Two steps of the inflating procedure of a stent with balloon; configuration of the stent at the moment of insertion (left), inflated configuration (right).


The femoral incision sites are closed, and the patient is returned to the recovery room

for initial observation. Following that, the patient is sent to a regular hospital bed for

an overnight stay. The following morning the patient is discharged from the hospital.

A return visit is accomplished within the first week, when a repeat CT scan and plane

abdominal films are obtained in order to make certain that the graft is functioning

properly. The femoral incisions are usually well healed within one to two weeks, and

the patient returns to normal physical activity.

Step by step EVR procedure

Here a step-by-step explanation of the implantation of a stent-graft is given. The

example is based on the use of the AneuRx stent-graft, but with the exception of

few details (for instance the configuration of the radiopaque markers) the procedure is

absolutely general.

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1. Insertion of the primary stent graft delivery catheter into the vessel, maintaining continual

fluoroscopy for proper positioning above the renal

arteries. Traction or a slow pull on the wire is essential to facilitate device tracking.


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2.This kind of stent has a special cone shaped part to help the

surgeon during the deployment. The catheter’s nose cone has to

be placed at, or immediately above, the renal arteries. The

crosshole of the nose cone should appear fully round when

aligned. The top three radiopaque markers have to be

positioned towards the contralateral side.

3. In this phase the graft cover is retracted 2-3 cm until it is

possible to see the four proximal radiopaque markers.

It is essential to watch for possible movement via

fluoroscopy.


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4. Small rotational adjustments with the delivery catheter can still be made in this phase to align the radiopaque markers.

An angio check via the contralateral straight catheter should be performed in order to confirm the position of the

stent graft relative to the lowest artery. After the adjustments the straight

angiographic catheter has to be pulled back into the abdominal

aortic aneurysm.

5. The retraction of graft cover continues until this is just

below the distal radiopaque marker. This position is crucial and must be carefully checked with fluoroscopy to assure safe

deployment.


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6. Insertion of the cotralateral delivery catheter into the

sheath. This phase requires good experience, actually the

delivery catheter has to be inserted well into the gate area

and this is an area that is perpendicular to the images’

plane (the area is seen as a line on the video).

7. The delivery catheter must be aligned within the four

radiopaque markers of the pant leg in the mid- or upper

portion of the gate.


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8. The deployment of the stent graft has to be executed under

continuous fluoroscopy, watching carefully for any position changes.

Deployment of the iliac leg continues until the graft cover is just below the distal radiopaque

marker on the iliac leg.

9. Deployment completed. Accurate and secure proximal and distal attachment must be ensured to prevent endoleak

formation.


3.4 Drawbacks and follow up

Open surgery

The main drawbacks of the classic operation are the need for laparotomy, general

anesthesia, a hospital stay of 7-10 days, intensive care facilities and blood

transfusions. Despite the use of risk-factor determination, surgical repair of AAA is

still associated with unexpected peri- and post-operative complications.

Some of the reasons why the classical operation of resection and prosthetic

engraftment are associated with a significant morbidity in high-risk patients include

the following:

Aortic aneurysmectomy is a major surgical intervention requiring extensive

retroperitoneal dissection

Blood loss may be significant during the procedure

Access is needed through a full-length laparotomy incision extending from

the xiphisternum to the pubis. This predisposes to important fluid losses and

hypothermia during the procedure

Clamping and declamping of the aneurysm neck result in hypo tension

associated with major haemodynamic disturbances

Respiratory problems associated with general anesthesia and major surgery.

The results of conventional surgical repair of AAA are durable and the danger of

rupture is eliminated, these aspects are fundamental to understand why this kind of

operation is still performed and is often preferred to the endovascular procedure.

Moreover EVR of AAA is currently still considered an investigational technique

under validation worldwide and results of long-term studies and outcome are slowly

becoming available.

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EVR

The Achilles heel of EVR is the development of procedural, peri-procedural or late

endoleaks and endotension (when aneurysms grow even in absence of any detectable

endoleak) due to anatomical factors. An endoleak refers to incomplete sealing of the

stent allowing back bleeding into the paraprosthetic space. The incidence varies from

7-10% in major series, unfortunately the need for additional interventions to seal the

leaks increases the cost \ benefit ratio of EVR of AAA [Don F. du Toit, 1999].

Before analyzing these important drawbacks of the endovascular procedure, it is

useful to distinguish four different types of endoleak.

Endoleak Type I: flow between the stent-graft and the wall of the aneurysm

related to the graft device itself (fig. 3.13).

Endoleak Type II: retrograde flow from collateral branches, this leak appears

to have a greater tendency to seal by spontaneous thrombus (fig. 3.14).

Endoleak Type III: due to fabric tears, graft disconnection or disintegration

(fig.3.15).

Endoleak Type IV: flow through the graft presumed to be associated with

graft wall “permeability\porosity” (fig. 3.16).

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Fig. 3.13 Perigraft-leaks

Type IbType Ia

With drainage

Blindend to

end


Endoleaks

The definition of initial technical success with endovascular techniques in the

management of aneurysms includes complete exclusion of the sac, reduction of intra-

aneurysm pressure, restoration of normal blood flow and prevention of rupture. The

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Fig. 3.14 Collateral leaks

Type IIa Type IIb

Blindend to

end

With drainage

Type III Type IV

Fig. 3.15 Mid-graft leak Fig. 3.16 Graft-porosity leak


fixation points at the ends of a stent-graft must be in complete apposition with the

normal vessel wall without thrombus interposition to achieve these goals. If this is not

achieved, sealing at the fixation points will be incomplete or temporary [J. C. Parodi

et al., 2001]. Endoleaks have been reported in 7% to 37% of endovascular aortic

aneurysm repair [B. Marty et al., 1998].

An endoleak involves the failure of complete exclusion of the aneurysm with the

persistence of elevate pressures within the aneurysm sac. The flow due to an endoleak

may be caused by an incomplete seal at the graft ends or, between segments, by

thrombus interposition, by incomplete deployment, or by inappropriate sizing.

Finally, endoleaks that are not graft related may be seen with retrograde flow from

patent lumbar or inferior mesenteric arteries.

The presence of endoleaks without enlargement and, conversely, enlargement without

demonstrable endoleaks allow us to justify the concept of aneurysm sac

pressurization as a real cause of enlargement, ultimately leading to aneurysm rupture

[J. C. Parodi et al., 2001].

Two factors produce pressurization inside the sac:

1. pressure inside the endograft that is transmitted by pulsation inside a semi-

rigid container (the aneurysm sac);

2. the intra-abdominal pressure.

The presence of an endoleak causes a significant increase in aneurysm pressure (mean

pressure and diastolic pressure), the extent of which is directly proportional to the

endoleak size, even a small size endoleak causes considerable pressure in the sac,

which in the clinical settings could lead to aneurysm rupture.

La Place’s law dictates that the wall stress of an artery is proportional to the radius

and intraluminal pressure and inversely proportional to wall thickness. This concept

predicts that increasing blood pressure or sac diameter should increase wall tension

and also the risk of rupture.

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Endoleaks are usually situated at the proximal stent attachment site and produce a

small perigraft channel with outflow through a partially thrombosed aneurysm sac [J.

C. Parodi et al., 2001]. The pressure in the thrombus remains low, but at the distal

end, the pressure level suddenly increases up to systemic level and pulsatility

immediately.

The addition of extra human fibrinogen into the aneurysm sac prohibits the formation

of thrombus inside the aneurysm.

An open endoleak produces a mean pressure inside the aneurysm identical to that in

the systemic circulation. This level of aneurysm pressure is independent of the size of

the endoleak. As soon as the endoleak thromboses, the mean aneurysm pressure

declines to zero.

The belief that large endoleaks are more dangerous than small ones might be

explained not by the higher pressure but by the presence of pulsatile pressure [G. W.

H. Schurink et al., 2000].

In conclusion, an open endoleak results in systemic mean pressure inside the sac. If

the aneurysm is not thrombosed, pulse pressure is present within the sac, but the

magnitude depends on the diameter of the endoleak.

Pulse pressure is absent within the sac when it is completely or partially thrombosed.

A thrombosed endoleak (endoleak in presence of thrombus that occludes the

bleeding) results in a decrease in mean pressure and the absence of pulse pressure in

the sac. The pressure decrease is more evident for small endoleaks.

Successful embolization of an endoleak by Histoacryl glue or Gelfoam reduces the

mean pressure in the sac and may be a useful therapeutic option when there is

progressive aneurysm growth [G. W. H. Schurink et al., 2000].

Endotension

Endotension has been recently described and defined as a persistent or recurrent

pressurization of the aneurysm sac after endovascular repair.

Transmission of pressure through thrombus or artheroma at the proximal attachment

site is a possible mechanism of endotension.

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It has been proposed that endotension may account for cases of aneurysm rupture in

the absence of endoleak and that aneurysms that enlarge or fail to decrease in size

may remain pressurized [C. S. Skillern et al., 2002].

Although the concept of endotension seems logical, it has not yet been shown

experimentally.

The mechanism for the endotension appears to be the transmission of aortic pressure

to the aneurysm sac through the attachment site failure.

The presence of endotension within the aneurysm sac after endovascular AAA repair

may signify treatment failure and risk of aneurysm rupture. Rupture may not lead to

catastrophic haemorrhage if the proximal and distal stent graft attachment sites

remain secure. However, endotension may also be the result of a sealed Type I

endoleak, and rupture could have disastrous consequences in that situation.

Pressure transmission may be related to porous graft fabrics. Also, graft materials

have previously been responsible for the local production of serous fluid by

transudation through a polytetrafluoroethylene (PTFE) graft used at open AAA

repair.

The mechanism for aneurysm enlargement remains unclear, but it is postulated to be

due to pressure transmission through thrombus after endoleak thrombosis [C. S.

Skillern et al., 2002].

Anatomical factors

Because of peculiar aneurysm anatomy detected in 70-80% of cases [Don F. du Toit,

1999], not all aneurysms can be safely treated by the elective endovascular route.

Moreover, the requirement to customize the device to specific aneurysm dimensions

precludes the use of current devices to large extent in the urgent or emergency

situation. In order to obtain a leak-free attachment, besides a correct sizing of the

prosthesis, it is important to ensure a secure anchorage; two are the critical landing

zones: the proximal and the distal necks. In fig. 3.17 and 3.18 the different

geometrical limitations are shown [Don F. du Toit, 1999].

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52

Fig. 3.17 Neck region. (A): Renal ostia originating at different levels. (B): Aneurysmal dilatation at the neck wit suprarenal extension. (C): Short conical

neck. (D): Short neck. (E): Reverse conical neck. (F): Aberrant renal arteries. (G): Angulated neck and aberrant arteries. (H): Concomitant renal artery stenosis. (I): Juxtarenal aneurysm formation. (J): Juxtarenal thrombus formation. (K, L, M, N,

O, P): Degree of angulations. (Q): Large aneurysm with intramural thrombus. (R): Posterior plaque. (S): Ulceration. (T): Thrombus.


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Fig. 3.18 Distal region. (A): Stenosis. (B): Hypoplastic segment. (C): Ipsilateral occlusion. (D): Intraluminal thrombus, tortuosity. (E): Bilateral angulations. (F):

Thrombus. (G): Unilateral iliac ectasia. (H): Unilateral stenosis, contralateral estasia. (I): Bilateral common iliac aneurysms. (J): Aorto-iliac stenosis and angulations. (K):

Hypogastric artery occlusions and stenosis. (L): Unilateral short iliac segment and contralateral angulations. (M): Concomitant iliac aneurysms. (N) : Common iliac

aneurysm and contralateral angulations. (O): Isolated internal iliac artery aneurysm. (P): Catheter perforation of iliac vessel during intubation.

Documents

SURGICAL TECHNIQUES 3.doc · Web viewA synthetic graft-usually a straight, Dacron woven tube is sutured to the aorta above and below the aneurysm (fig. 3.4). After the aortic graft